ON THE APPROACH TO STEADY-STATES OF REACTING SYSTEMS IN THE CONTINUOUS STIRRED TANK REACTOR

A theoretical investigation is presented of the approach of chemical reactions to their steady states in a continuous stirred tank reactor (CSTR). The define approach time t// epsilon which is a measure of the time required for any perturbation to decrease below a certain value where epsilon equals 1/e is a convenient choice for linear networks. It is shown analytically for any first order network that the approach time is less than or equal to the average residence time but never longer regardless whether ″overshoot″ or ″false start″ occurs if the sum of the initial CSTR concentrations does not exceed the sum of the input concentrations. For higher order single step CSTR reactions we present analytical solutions for small perturbations from their steady states.